A golf club head having a viscoelastic body on the rear surface of a face plate which forms a face surface has been proposed to improve the hitting impression or adjust the hitting sound on impact (Japanese Patent Laid-Open Nos. 2004-89434 and 2005-218510). When the viscoelastic body is loaded on the rear surface of the face plate, the vibration on impact is absorbed by the viscoelastic body to improve the hitting impression and decrease the hitting sound that is offensive to the player's ear.
In order to effectively control vibration on impact by a viscoelastic body, the viscoelastic body is desirably in tight contact with the rear surface of a face plate. For this structure, desirably, the viscoelastic body is inserted in a compressed state in the inserting space formed by a head main body and the face plate of a golf club head.
In order to insert the viscoelastic body in a compressed state, the viscoelastic body needs to be formed slightly larger than the inserting space so as to ensure the compression margin. If a large compression margin is ensured, however, when fixing the face plate to the head main body, the head main body and face plate may bite into the viscoelastic body. This interferes with the assembly operation of the golf club head. In contrast, if a small compression margin is ensured, the tight contact between the viscoelastic body and face plate decreases, or the tight contact area between the viscoelastic body and face plate decreases.